Simplify the following expression: $x = \dfrac{k}{7} + \dfrac{k}{2}$
Solution: In order to add expressions, they must have a common denominator. The smallest common denominator is the least common multiple of $7$ and $2$ $\lcm(7, 2) = 14$ $ x = \dfrac{2}{2} \cdot \dfrac{k}{7} + \dfrac{7}{7} \cdot \dfrac{k}{2} $ $x = \dfrac{2k}{14} + \dfrac{7k}{14}$ $x = \dfrac{2k +7k}{14}$ $x = \dfrac{9k}{14}$